一种快速的彩色图像矢量中值滤波算法

文章提出一种新的快速矢量中值滤波算法。首先，求取象素的方向区域距离测度并将滤波窗口划分为两个子窗口：然后，在子窗口内进行矢量中值滤波。实验结果表明，该算法速度快，具有较好的滤波效果。     

基于边缘保持滤波的Canny彩色图像边缘检测方法

提出了基于边缘保持滤波的Canny彩色图像边缘检测方法。该方法利用了HSV颜色空间信道相关性低的优点,结合Canny算子定位准确的优点和边缘保持滤波理论,用边缘保持滤波取代传统的高斯滤波,用梯度矢量计算法替代传统的梯度标量计算法,从而增强了在平滑过程中对图像边缘的保持,最大程度保留了色彩的差异信息,实现了彩色图像边缘的自适应提取。实验结果证明,该方法将灰度空间的Canny算法推广到彩色矢量空间,充分利用了彩色信息,对彩色图像边缘提取具有较好的检测精度和准确度。     

Quaternion switching filter for impulse noise reduction in color image

A novel approach to impulse noise reduction in color image is introduced in this paper. By applying the quaternion unit transform theory, the difference between two color pixels can be represented in the quaternion form. Based on the difference mentioned above, an efficient filter that can switch between the vector median filter (VMF) and the identity filter (no filtering operation) is proposed. Extensive simulation result indicates that the proposed filter achieves a trade-off between noise suppression and detail preservation in both correlated and uncorrelated impulse noise scenarios when compared with other widely used filters. Furthermore, the computational complexity analysis shows that the proposed filter is quite efficient.     

A new approach to vector median filtering based on space fillingcurves

The availability of a wide set of multidimensional information sources in different application fields (e.g., color cameras, multispectral remote sensing imagery devices, etc.) is the basis for the interest of image processing research on extensions of scalar nonlinear filtering approaches to multidimensional data filtering. A new approach to multidimensional median filtering is presented. The method is structured into two steps. Absolute sorting of the vectorial space based on Peano space filling curves is proposed as a preliminary step in order to map vectorial data onto an appropriate one-dimensional (1-D) space. Then, a scalar median filtering operation is applied. The main advantage of the proposed approach is the computational efficiency of the absolute sorting step, which makes the method globally faster than existing median filtering techniques. This is particularly important when dealing with a large amount of data (e.g., image sequences). Presented results also show that the filtering performances of the proposed approach are comparable with those of vector median filters presented in the literature.     

Vector median deblurring filter for colour image restoration

A new technique is described which couples median filtering and image deblurring techniques to filter noisy images without introducing defocusing side effects. To deal with colour images a vector median filtering procedure is proposed. Using this procedure a better edge preserving filter is obtained which does not introduce new colours. The deblurring operation is performed componentwise by fitting an ARMA model to the image. The AR part of the model estimates the image and the MA part estimates the blurring function. Finally, the MA part is inverted and applied to remove the blur introduced by the median filter.<>     

一种改进的快速矢量中值滤波器

提出了一种改进的快速矢量巾值滤波器(IFIVF,improved fast impulsive vector filter).IFIVF以FIVF为基础,通过peer group和边缘检测技术构建新的噪声检测器.与其它矢量中值滤波器(VMF)相比,新的噪声检测方法使得IFIVF不但可以对彩色图像中的随机和固定脉冲噪声进行有效压制,还可以进一步提高FIVF的滤波视觉效果.     

矢量对偶形态学算子

对偶性是形态学算子的重要性质之一,且具有重要应用.现有的矢量形态学算子均难以满足对偶性,从而限制了矢量数学形态学理论的发展及应用.为了解决该问题,研究了现有矢量形态学算子的性质,发现彩色空间和矢量排序算法是导致矢量形态学算子难以满足对偶性的两个关键因素.通过选用对称彩色空间,利用矢量对称距离实现了具有对偶特性的矢量形态学算子.为了验证矢量对偶形态学算子的性能,给出了满足对偶特性的矢量形态学滤波及梯度算子,并将其应用到彩色图像滤波及边缘检测中.实验结果表明,矢量对偶形态学算子较传统的矢量形态学算子具有更好的对称性,对噪声条件下的图像进行滤波及边缘检测,均获得了更好的处理效果.     

Impulsive noise filtering based on noise detection in corrupted digital color images

This paper is an enhancement to our earlier research with grey-scale images. In this paper, we propose two new detection-estimation based image filtering algorithms that effectively remove corrupted pixels with impulsive noise in digital color images. The existing methods for enhancing corrupted color images typically possess inherent problems in computation time and smoothing out edges because all pixels are filtered. Our proposed algorithms first classify corrupted pixels in each channel or in each pixel. Because marginal or vector median filtering is only performed for the classified pixels, the process is computationally efficient, and edges are preserved well. In addition, because there is no appropriate criterion to evaluate the performance of impulsive noise detectors for color images, the objective comparison of noise detectors is difficult. Thus, we introduce a new efficiency factor for comparing the performance of noise detectors in digital color images. Simulation results show that the proposed algorithms perform better than existing methods, in both objective and subjective evaluations.This work was supported by the Korea Science & Engineering Foundation (KOSEF) under grant no. 981-0912-057-2.     

机场跑道图像去雾增强算法及其实现

机场跑道场景下,由于雾、霾等恶劣天气以及大气散射的作用,使拍摄的图像对比度降低,颜色退化,物体特征难以辨认,影响机场跑道图像的异物检测与识别,带来一些安全隐患。针对上述问题,提出基于双线性插值和中值滤波的改进的引导滤波算法,提高图像对比度和处理速度,利于机场跑道异物检测与识别。仿真结果表明,改进的引导滤波算法与已有算法相比,处理速度提高了2~3倍,且图像彩色值分布更广,直方图更均匀。该算法拥有良好的边缘保持性,在细节增强方面有很好的指导意义。随后将改进的引导滤波算法移植到数字信号处理器( DSP)平台上,以满足实际工程应用对小型化的需求。     

基于颜色矢量角的彩色图像检索算法研究

通过分析利用颜色直方图进行图像检索时存在的问题,提出了一种基于图像边缘空间分布特征的图像检索算法。即利用颜色矢量角对亮度不敏感,对色度和饱和度敏感的特性来提取图像的边缘信息。在图像的边缘空间,提取图像边缘点的颜色矢量角直方图,以此来描述图像的内容。该算法充分利用了图像的颜色信息、边缘信息及形状信息,实验表明该算法具有较好的光照不变性、尺度不变性、平移不变性和旋转不变性。     

Monochromatic-Based Method for Impulse Noise Detection and Suppression in Color Images

A new method to detect and reduce the impulse noise in color images is presented in this paper. The method consists of two stages: detection and filtering. Since each of the individual channels (components) of the color image can be considered as a monochrome image, both stages are applied to each channel separately, and then the individual results are combined into one output image. The corrupted pixels are detected in the first stage based on a proposed innovative switching technique. The noise-free pixels are copied to their corresponding locations in the output image. In the second stage, average filtering is applied only to those pixels which are determined to be noisy in the first stage, and only noise-free pixel values are involved in calculating this average. The size of the sliding window depends on the estimated noise density and is very small even for high noise densities. The proposed method is effective in noise reduction while preserving edge details and color chromaticity. Simulation results show that the proposed method outperforms all the tested existing state-of-the-art methods used in digital color image restoration in both standard objective measurements and perceived image quality.     

Nonlinear multivariate image filtering techniques

In this paper, nonlinear multivariate image filtering techniques are proposed to handle color images corrupted by noise. First, we briefly review the principle of reduced ordering (R-ordering) and then define three R-orderings by selecting different central locations. Considering noise attenuation, edge preservation, and detail retention, R-ordering based multivariate filters are designed by combining the R-ordering schemes. To implement color image filtering more effectively, we develop them into a locally adaptive version. The output of the adaptive filter is the closest sample to a central location that is a weighted linear combination of the mean, the marginal median, and the center sample. As a result, we study an adaptive hybrid multivariate (AHM) filter consisting of the mean filter, the marginal median filter, and the identity filter. The performance of the two adaptive filtering techniques is compared with that of some nonadaptive ones. The examples of color image filtering show that the adaptive multivariate image filtering gives a rather good performance improvement.     

一种新的低照度彩色图像降噪算法

针对低照度监控图像存在大量噪声的情况,按照视觉心理感知特性选择HSV颜色空间,在此空间提出了一种新的低照度彩色图像降噪的算法,保持色调不变,针对饱和度和亮度分量的不同特征,分别采用了中值滤波和基于边缘提取的降噪方法。实验结果表明该算法在保持了色调和边缘不变的同时,提高了图像信噪比,降噪效果明显。     

Efficient edge-preserving algorithm for color contrast enhancement with application to color image segmentation

In this paper, a new and efficient edge-preserving algorithm is presented for color contrast enhancement in CIE Lu^′v^′ color space. The proposed algorithm not only can enhance the color contrast as the previous algorithm does, but also has an edge-preservation effect. In addition, the spurious edge points occurred due to the color contrast enhancement can be well reduced using the proposed algorithm. This is the first edge-preserving algorithm for color contrast enhancement in color space. Furthermore, a novel color image segmentation algorithm is presented to justify the edge-preservation benefit of the proposed color contrast enhancement algorithm. Based on some real images, experimental results demonstrate the advantages of color contrast enhancement, edge-preservation effect, and segmentation result in our proposed algorithm.     

基于边缘检测与双边滤波的彩色图像去噪

 针对彩色图像双边滤波去噪方法存在的不足,本文提出一种边缘检测与双边滤波相结合的彩色图像去噪方法.首先利用细胞神经网络(CNN)模型导出一种新的彩色图像分块自适应边缘检测算法,继承了CNN灰度边缘检测算法定位准确的优点,又弥补了CNN现有算法不能直接处理彩色图像的空白.接下来提出一种针对图像增强的边缘滤波算法,通过两级边缘检测满足去噪不同阶段对边缘检测的不同要求.在此基础上,用改进的双边滤波器对彩色图像进行去噪,通过非抗噪边缘图对噪声范围进行定位,以缩小双边滤波的范围,减少去噪过程带来的图像模糊,并且对双边滤波加权平均方式进行改进,减小噪声点本身的权重,降低高频噪声的影响.最后根据滤波后的去噪边缘图对彩色图像进行增强.实验结果表明,文中方法在有效去除噪声的同时保护和增强了图像中的边缘.     

Nonlinear processing and analysis of angular signals

Physical quantities referring to angles, like vector direction, color hue, etc., exhibit an inherently periodic nature. Due to this periodicity, digital filters and edge operators proposed for data on the line cannot be applied on such data. We introduce filters for angular signals (circular mean, circular median, circular a-trimmed mean, circular modified trimmed mean). Particular emphasis is given to the circular median filter, for which some interesting properties are derived. We also use estimators of circular dispersion to introduce edge detectors for angular signals. Three variations for the extension of quasirange to circular data are proposed, and expressions for their output PDF are derived. These “circular” quasiranges have good and user-controlled properties as edge detectors in noisy angular signals. The performance of the proposed edge operators is evaluated on angular edges, using certain quantitative criteria. Finally, a series of experiments featuring one-dimensional (1-D) angular signals and hue images is used to illustrate the operation of the new filters and edge detectors     

一种基于改进块匹配算法的运动车辆检测

针对传统块匹配算法计算量大、光照变化较敏感和实时性差的缺陷,本文对块匹配算法进行了相关研究,提出了改进算法。首先把两幅彩色图像转化为灰度图像,并通过概率松弛标记算法获得边缘图像,计算相邻两幅图像的差分图像得到运动区域,然后将差分图像与边缘检测图像相与得到运动区域的边缘信息,再进行匹配得到位移矢量场并对其进行矢量中值滤波,最后通过顺序区域增长将运动车辆分割出来。实验结果表明:本文方法相对于传统方法平均检测时间降低约58ms,而平均检测率提高了约6.7%。这种算法鲁棒性强、实时性好。     

基于视觉感知模型修正的彩色图像边缘检测

在彩色图像边缘检测过程中,准确检测低照度区域的细节边缘是一个难题.提出了一种基于视觉感知模型修正的彩色图像边缘检测方法.由于视觉感知彩色空间中的色调分量具有圆形特性,导致伪边缘问题,利用色调距离计算色调图像的梯度以去除伪边缘,并根据饱和度的非线性函数控制色调分量的梯度,最后利用修正的视觉感知模型计算矢量梯度以获取彩色图像的边缘.实验结果表明,新的彩色边缘检测方法较现有方法能提高彩色图像的边缘检测精度,尤其对于低照度区域的细节边缘具有较好的响应.     

Local quaternion PHT based robust color image watermarking algorithm

It is a challenging work to design a robust localized color image watermarking scheme against desynchronization attacks. There are two main drawbacks indwelled in current localized color image watermarking: firstly, the pure gray-based feature points detectors were utilized, in which the important color information is ignored. Secondly, the watermarking algorithms were designed mainly to mark the image luminance component only, in which the significant color channels correlation are neglected. In this paper, we propose a robust color image watermarking algorithm using local quaternion PHT (Polar Harmonic Transform), which is invariant to various noises, local geometric transformations, and color variations. Firstly, the stable color image feature points are extracted by using new color image feature point detector, in which the SIFER (Scale-Invariant Feature detector with Error Resilience) detector and color invariance model are incorporated. Then, the affine invariant local regions are built adaptively according to local image content variation. Finally, the digital watermark is embedded into the local regions by modulating the invariant quaternion PHT modulus coefficients. Experiments are carried out on a color image set collected from Internet, and the extensive experimental works have shown that the proposed color image watermarking is not only invisible and robust against common image processing operations such as median filtering, noise adding, and JPEG compression, but also has conquered those challenging desynchronization attacks.     

基于图像传感器的图像画质增强算法研究

针对图像在传输过程中易引入噪声、色彩质量下降、中值滤波导致图像细节丢失和均值滤波出现模糊等问题,提出了一种可以应用于CMOS图像传感器的图像画质增强和滤波算法.该算法对插值后的Bayer图像数据进行一维空间的增强和降噪处理,首先将图像从RGB空间转换到YUV空间,在Y通道上用改进的直方图均衡化方法实现图像明暗程度的对比度增强调节,对U、V通道采用分段式线性调节方法实现饱和度调节;然后对Y通道进行自适应降噪,对U、V通道进行加权中值滤波降噪,以满足后续处理对图像质量的要求;最后在Y通道上,采用基于Laplace算子的锐化掩模进行锐化处理,保证图像的细节清晰可见.实验结果表明:从图像视觉效果来看,相比单独使用中值和均值滤波,所提出的自适应滤波得到的效果更好,图像细节保存较好、模糊程度低、图像更为清晰,且色彩质量更高.通过对比峰值信噪比(PSNR),对混合噪声进行处理时,该滤波算法的PSNR优于中值和均值滤波,有效地抑制了噪声.整个算法在一维邻域空间进行,更容易在有限的硬件上实现较好的图像处理结果,满足小面积低功耗的要求.